When JUnitShell wraps exceptions from remote browsers, be sure to copy the cause.

Review by: jat (TBR)

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@5009 8db76d5a-ed1c-0410-87a9-c151d255dfc7
diff --git a/user/src/com/google/gwt/junit/JUnitShell.java b/user/src/com/google/gwt/junit/JUnitShell.java
index 700acd4..6563f8c 100644
--- a/user/src/com/google/gwt/junit/JUnitShell.java
+++ b/user/src/com/google/gwt/junit/JUnitShell.java
@@ -702,6 +702,7 @@
           AssertionFailedError newException = new AssertionFailedError(msg
               + "\n" + exception.getMessage());
           newException.setStackTrace(exception.getStackTrace());
+          newException.initCause(exception.getCause());
           exception = newException;
         } else {
           exception = new RuntimeException(msg, exception);